[LTP] [PATCH v4] Add test case to cover the setting resource limit64 for process

[Chunfu Wen]

From: chunfuwen <chwen@redhat.com>

The test ensures that the process gets the correct signals in the correct order:

First, it should get SIGXCPU after reaching the soft CPU time limit64.
Then, if the CPU time exceeds the hard limit, it should receive SIGKILL

Signed-off-by: chunfuwen <chwen@redhat.com>
---
 include/lapi/resource.h                       | 28 ++++++++++++
 .../kernel/syscalls/setrlimit/setrlimit06.c   | 44 ++++++++++++++-----
 2 files changed, 60 insertions(+), 12 deletions(-)
 create mode 100644 include/lapi/resource.h

diff --git a/include/lapi/resource.h b/include/lapi/resource.h
new file mode 100644
index 000000000..a9bc57a0a
--- /dev/null
+++ b/include/lapi/resource.h
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2025 Red Hat Inc. All Rights Reserved.
+ * Author: Chunfu Wen <chwen@redhat.com>
+ */
+
+#ifndef LAPI_RESOURCE_H__
+#define LAPI_RESOURCE_H__
+
+#define _GNU_SOURCE
+
+#include "config.h"
+#include <sys/resource.h>
+#include "lapi/syscalls.h"
+
+#ifndef HAVE_STRUCT_RLIMIT64
+struct rlimit64 {
+        uint64_t rlim_cur;
+        uint64_t rlim_max;
+};
+#endif
+
+static int setrlimit_u64(int resource, const struct rlimit64 *rlim)
+{
+        return tst_syscall(__NR_prlimit64, 0, resource, rlim, NULL);
+}
+
+#endif /* LAPI_RESOURCE_H__ */
diff --git a/testcases/kernel/syscalls/setrlimit/setrlimit06.c b/testcases/kernel/syscalls/setrlimit/setrlimit06.c
index 9ff515d81..ded550973 100644
--- a/testcases/kernel/syscalls/setrlimit/setrlimit06.c
+++ b/testcases/kernel/syscalls/setrlimit/setrlimit06.c
@@ -4,12 +4,12 @@
  * Author: Xiao Yang <yangx.jy@cn.fujitsu.com>
  */
 
-/*
- * Description:
+/*\
  * Set CPU time limit for a process and check its behavior
- * after reaching CPU time limit.
- * 1) Process got SIGXCPU after reaching soft limit of CPU time.
- * 2) Process got SIGKILL after reaching hard limit of CPU time.
+ * after reaching CPU time limit
+ *
+ * - Process got SIGXCPU after reaching soft limit of CPU time
+ * - Process got SIGKILL after reaching hard limit of CPU time
  *
  * Note:
  * This is also a regression test for the following kernel bug:
@@ -27,6 +27,12 @@
 #include <sys/mman.h>
 
 #include "tst_test.h"
+#include "lapi/resource.h"
+
+#define TEST_VARIANTS 2
+
+static struct rlimit *rlim;
+static struct rlimit64 *rlim_64;
 
 static int *end;
 
@@ -37,6 +43,11 @@ static void sighandler(int sig)
 
 static void setup(void)
 {
+	rlim->rlim_cur = 1;
+	rlim->rlim_max = 2;
+	rlim_64->rlim_cur = 1;
+	rlim_64->rlim_max = 2;
+
 	SAFE_SIGNAL(SIGXCPU, sighandler);
 
 	end = SAFE_MMAP(NULL, sizeof(int), PROT_READ | PROT_WRITE,
@@ -58,12 +69,14 @@ static void verify_setrlimit(void)
 
 	pid = SAFE_FORK();
 	if (!pid) {
-		struct rlimit rlim = {
-			.rlim_cur = 1,
-			.rlim_max = 2,
-		};
-
-		TEST(setrlimit(RLIMIT_CPU, &rlim));
+		switch (tst_variant) {
+		case 0:
+			TEST(setrlimit(RLIMIT_CPU, rlim));
+		break;
+		case 1:
+			TEST(setrlimit_u64(RLIMIT_CPU, rlim_64));
+		break;
+		}
 		if (TST_RET == -1) {
 			tst_res(TFAIL | TTERRNO,
 				"setrlimit(RLIMIT_CPU) failed");
@@ -72,7 +85,8 @@ static void verify_setrlimit(void)
 
 		alarm(20);
 
-		while (1);
+		while (1)
+			;
 	}
 
 	SAFE_WAITPID(pid, &status, 0);
@@ -112,6 +126,12 @@ static void verify_setrlimit(void)
 static struct tst_test test = {
 	.test_all = verify_setrlimit,
 	.setup = setup,
+	.test_variants = TEST_VARIANTS,
+	.bufs = (struct tst_buffers []) {
+		{&rlim, .size = sizeof(*rlim)},
+		{&rlim_64, .size = sizeof(*rlim_64)},
+		{}
+	},
 	.cleanup = cleanup,
 	.forks_child = 1,
 	.tags = (const struct tst_tag[]) {
-- 
2.43.5